fix fetch and store with multiple locations

Promise.race resolve or rejects with the first promise that answers.
We now return the first promise that fulfills after all promises have
settled.

src/files.js

@@ -4,7 +4,7 @@ import { config } from './config.js'
 
 async function fetchData (path, baseUrl) {
   const response = await fetch(new URL(path, baseUrl))
-  if (!response.ok) return null
+  if (!response.ok) throw new Error('Error fetching file')
   const content = await response.buffer()
   const sha256Sum = crypto.createHash('sha256').update(content).digest('base64')
   return [path, {
@@ -46,7 +46,9 @@ class FileCache {
 
   async fetchAndStore (path) {
     if (config.urls.length === 0) await config.load()
-    const [key, value] = await Promise.race(config.urls.map(baseUrl => fetchData(path, baseUrl)))
+    const [[key, value]] =
+      (await Promise.allSettled(config.urls.map(baseUrl => fetchData(path, baseUrl))))
+        .filter(r => r.status === 'fulfilled').map(r => r.value)
     this._cache[key] = value
     return value
   }